This invention relates generally to surgical instruments and, more particularly, to a trocar seal system. The trocar seal system of the present invention permits instruments of different sizes to be inserted into a trocar without breaking the gas seal created by the trocar. Unlike known trocar converters, the trocar seal system of the present invention is automatic and does not require any manipulation by the surgeon. The surgeon merely inserts the desired size of instrument and the trocar seal system provides the appropriate seal.
A trocar, in general, is a surgical instrument that can be used to create and maintain small hole-like incisions in a body cavity. These incisions are then used to introduce other surgical instruments into the body cavity to perform various surgical procedures. Conventional trocars include an obturator and a cannula. The obturator is a structure for penetrating a body wall to create the incision into the body cavity. The obturator can have either a sharp point or blunt tip. The cannula is a tube-like structure that is left in the incision made by the obturator to maintain the incision after the obturator is removed. Typically, the trocar comes as a unit that includes the obturator fitted inside of the cannula
In surgical procedures involving trocars, the body cavity is generally inflated with carbon dioxide gas. Inflation of the body cavity with this gas creates a working "pocket" within the cavity and limits surgical instruments inserted through the cannula from puncturing internal organs. To maintain the cavity in an inflated state throughout the procedure, conventional cannulas include flaps and annular seals that prevent gas from escaping from the cavity when the obturator is withdrawn from the cannula and when other surgical instruments are subsequently inserted and withdrawn from the cannula. The flaps and annular seals are unable to prevent the escape of the gas if the diameter of the surgical instrument is less than the diameter of the hole in the annular seal. Thus, in a typical procedure a surgeon is limited in the size of instruments that can be inserted through a given cannula. Many times a surgeon wants to choose from a variety of surgical instruments having different diameters. With conventional trocars this requires that the surgeon either insert a number of cannulas each having a different size annular seal if he wishes to use surgical instruments with different diameters, or that the surgeon change the hole size by snapping one of several trocar converters, each having an annular seal with a different diameter hole, onto the cannula The latter option requires a collection of trocar converters and continuous changing of the trocar converters for various instrument sizes.
Therefore, it is desirable to provide a trocar that is capable of easily accommodating surgical instruments having different diameters while maintaining the inflated state of the body cavity.